Typically, in the construction of homes it is important to protect roofs from leaks due to ice and rain. Traditionally, felt paper was secured to wooden roofs underneath shingles. The felt paper would absorb ice or water that penetrated the shingles, preventing it from reaching the underlying wood. Nailing the felt paper to the roof, however, caused spaces around the nail through which water could seep. The water could follow the nail into the wood, causing leaks in the home. To solve this problem, water shields began to include an adhesive backing to fasten the shield to the wood, instead of using nails. The adhesive backing includes a peel-able strip which, when removed, exposes the adhesive layer for affixing the water shield to the unprotected wooden roof. The top of these water shields were made of a rubberized asphalt material, which created a gasket effect on the shaft of the nail driven through it. These water shields were successful in preventing many types of leaks.
In colder climates, however, ice dams can form and allow water to penetrate or flow under the water shield. For example, an ice dam can prevent melt-water from flowing downward off the roof, which can result in the water seeping into the house above the ice and water shield coverage area. Ice dams occur when snow accumulates on the roof of a house with inadequate insulation. Heat conducted through the insufficiently insulated roof, and warm air from the space below, warms the roof and melts the snow on areas of the roof that are above living spaces. It does not, however, melt the snow over cold areas, such as roof overhangs. In these situations, melt-water from the heated areas of the roof flows down the roof, under the blanket of snow, onto the overhang and into the gutter, where colder conditions permit it to freeze. Eventually, ice accumulates along the overhang and in the gutter. Snow that melts later cannot drain properly, backs up on the roof and can result in damaged ceilings, walls, roof structure, and insulation. To avoid this many building codes require a water shield covering the roof two feet into the living space.
Additionally, in the past, heating wires and cable-based deicing systems have been disposed on top of the shingles on roofs. These remedial routes provide heat to melt channels in the deposited ice to restore drainage of water through accumulated ice and snow thereby preventing the problems resulting from ice dams. However, since the solution is topical and restricted to the formation of channels at selective areas under severe weather conditions, the efficacy of these solutions is not adequate to prevent leaks from ice dam formation. Furthermore, heating wires and cable-based deicing systems are visible and aesthetically unsightly, easily damaged, and needed to be replaced frequently.
A need for a robust solution that address the ice dam problem persists.